/Engine/Source/Runtime/Experimental/GeometryCollectionEngine/Public/GeometryCollection/GeometryCollectionObject.h
Find or add a auto instance mesh and return its index
const [FGeometryCollectionAutoInstanceMesh](API\Runtime\GeometryCollectionEngine\GeometryCollection\FGeometryCollect-_1) & GetAutoInstanceMesh ( int32 AutoInstanceMeshIndex ) const